Air return mechanism for a fastener driving machine



May 19, 1970 G. R. PERKINS 5 AIR RETURN MECHANISM FOR A FASTENER DRIVING MACHINE Filed Jan. 2 1968 5 Sheets-Sheet l INVENTOR.

GARY R. PERKINS ATTORNEY J. Walton Barker 3 2 w m a. G W r45 in I. F F v I 1 m 4 2 dflw /3 5 I55 7.\ 3 x w 6 3 5 1!. a w IMF 7117114 w 2 6 m l 14 I, a 1 I Y\ 6 I 7 G wvffdzfiwarlla 6 I 5 r x Rd F .U Ex A E a w l 8 WI HI U 4 6 v 4 May 19, 1970 G R. PERKINS 3,512,454

AIRRETURN MECHANISM FOR A FASTENER DRIVING MACHINE Filed Jan. 2, 1968 3 Sheets-Sheet 2 55 55 I, i 58 F I G I 54 4 57\ A I 68 5w- F 6.7 /5 4/. I II 50 49 ill /6 l5 69- l i l I I l 2 M- 4/ I I i l I I 1 1 INVENTOR.

GARY R- PERKINS BY J. Wdi'fon Bender ATTORNEY May 19, 1970 4 G. R. PERKINS 3,512,454

AIR RETURN MECHANISM FOR A FASTENER DRIVING MACHINE Filed Jan. 2, 1968 3 Sheets-Sheet 5 I INVENTOR.

GARY R PERKINS ATTORNEY United States Patent O York Filed Jan. 2, 1968, Ser. No. 699,986 Int. Cl. F15b 11/08, 13/04; Ffllb 11/02 U..S. Cl. 91-461 2 Claims FASTENER ABSTRACT OF THE DISCLOSURE A fastener driving machine is shown having a housing with a first chamber within the housing. A piston is sealingly and reciprocatingly movable within the first chamber. A first valve is utilized to permit pressure fluid to impinge upon one side of the piston and permit the piston to move in one direction. A trigger valve is connected to a conduit which is also connected to the first valve. Pressure air normally fills the first conduit and keeps the first valve in closed position. A second conduit is also connected to the trigger valve and is also normally filled with pressure air. The second conduit is also connected to the lower portion of the first chamber and to a second chamber. The second chamber has a second valve therewithin which is formed with an actuator which is sealingly and reciprocatingly movable therewithin. The actuator has two opposite faces one of which is larger in cross-sectional area than the other. The larger face is adjacent the second conduit and normally has pressure air impinging thereupon. The smaller face normally blocks a port within the chamber which is open to atmosphere. Pressure air also impinges on the smaller face of the actuator. Opening of the trigger valve will permit pressure air to open the first valve and allow pressure air to strike one side of the piston. The opening of the trigger valve will also move the actuator of the second valve into position wherein the port within the second chamber will be opened. Closing of the trigger valve will close the first valve and the second valve and thus will permit pressure air to return the piston to its normal rest position.

DESCRIPTION OF THE INVENTION This invention relates to an air return mechanism for a fastener driving machine. The air return mechanism of this invention is particularly adapted to be utilized in connection with the nailing machine which was invented by I. Walton Bader and is presently pending in the United States Patent Ofiice under Ser. No. 695,538, filed Dec. 4, 1967.

While the air return system of this invention is shown as applied to the said nailing machine referred to hereinabove the mechanism involved is obviously not limited to the structure shown and may be applied to various other types of fastener driving machines.

Heretofore, as shown in the prior art, there have been many types of air return mechanisms for fastener driving machines shown. However all of the prior art structures sufl ered from various disadvantages. In one type of prior art structure a double-faced piston was used. The driving face of the piston was made of greater operational area than the return face. Pressure air was always applied to the return face but not to the driving face. Thus, when driving pressure was applied, since the driving pressure was greater than the return pressure the piston was driven in the downward position while, when the pressure air was removed from the driving portion, the piston returned to its normal position.

Obviously a structure of this type has a number of disadvantages primarily due to the fact that the driving pressure is applied against the return pressure. Therefore a larger volume of air is required to drive the piston than would normally be necessary.

A second type of air return mechanism that is shown in the prior art utilizes sequential direction of pressure air to opposite sides of the piston. The pressure air is disposed within a conduit and a dual valve is provided within the conduit that sequentially directs the pressure air to opposite sides of the piston. Such a valve structure has been uniformly found to be unsatisfactory. It tends to get out of order quite easily, to leak, and to have a number of other disadvantages.

The air return system of this invention avoids the disadvantages of the prior art. In this mechanism a chamher is provided which contains a piston sealably movable therewithin. A first conduit is provided which is adapted to carry pressure fluid into the chamber against one side of the piston so as to cause the piston to move in one direction. An auxiliary valve is also provided within the conduit and means are provided for opening theauxiliary valve when pressure fluid is exhausted from the chamber and to close the auxiliary valve when pressure fluid is introduced into the chamber.

The movement of the auxiliary valve is timed to co incide with the movements of the valve utilized to per' mit pressure fluid to be introduced on one side of the piston to drive the same and thus a very simple and foolproof structure is provided.

The invention will now be further described by reference to the accompanying drawings which are made a part of this specification.

FIG. 1 is a longitudinal cross-sectional view of a fastener driving machine carrying the air return mechanism of this invention. Because of space limitations the auxiliary valve portion of the mechanism of this invention is not shown in FIG. 1. This mechanism is actually shown in FIG. 2.

FIG. 2 is a fragmentary detail cross-sectional view of the auxiliary valve portion of the air return mechanism of this invention.

FIG. 3 is a detail side elevational view of the auxiliary valve and associated parts showing the ports utilized within the second chamber to open the chamber to atmosphere. I

FIG. 4 is a detail perspective view of the actuator of the trigger valve of this invention. In this view the actuator is shown on an enlarged scale.

FIG. 5 is a view substantially similar to that shown in FIG. 1 but with the parts shown in the position that they assume as the pressure air commences to be applied to one side of the piston in order to drive the piston and perform work with the fastener driving machine. In this figure, as well, the auxiliary piston is not shown for clarity of illustration and this piston is shown in FIG. 6.

FIG. 6 is a detail cross-sectional view similar to that shown in FIG. 2 but showing the position of the actuating member of the auxiliary valve as the pressure air is applied to one side of the piston in order to perform work with the fastener driving machine.

FIG. 7 is a detail cross-sectional view, on an enlarged scale, showing the trigger valve of this invention and associated parts.

FIG. 8 is a view similar to that of FIGS. 1 and 5 but showing the position of the parts as the piston continues to move downwardly in order to perform work in connection with the machine of this invention.

FIG. 9 is a view similar to that of FIGS. 2. and 6 but with the position of the auxiliary valve shown to correspond with the piston position shown in FIG. 8.

FIG. 10 is a detail cross-sectional view of the trigger valve of this invention taken along lines 10-10 of FIG. 8.

The invention will now be further described by reference to the specific form thereof as shown in the accompanying drawings. In this connection, however, the reader is cautioned to note that the specific form of this invention as shown in the specification and drawings herein is merely for illustrative purposes and for purposes of example only. Various changes and modifications could be made thereto without departing from the spirit and scope of this invention.

Now referring to the specific form of the invention as shown in the accompanying drawings herein, the fastener driving machine 11 to which the air return mechanism of this invention is applied, is formed with a housing 12. Within housing 12 is a first chamber 13 within which a piston 14 is reciprocatingly movable. Piston 14 bears an O-ring 15 thereupon which is secured thereto within a groove 16. Thus piston 14 is sealingly disposed within chamber 13.

Connected to piston 14 by bolt 17 is a rod 18 which in turn bears an O-ring 19 so that rod 18 is also sealingly connected within housing 12.

A bumper 20 is provided to absorb the shock of a downward blow on piston 14.

Surrounding chamber 13 is a chamber 21 which is continuously supplied with pressure air during the operation of the fastener driving machine. The pressure air comes from a reservoir 22 which is joined to chamber 21 by conduit 23. Conduit 24 is joined to portion 25 of auxiliary valve chamber 26.

An additional conduit 27 is connected to portion 28 of auxiliary valve chamber 26 which conduit joins conduit 24 at 30 as shown in FIGS. 1, 5 and 8. In FIGS. 1, 5 and 8 of the drawings conduit 24 is also shown joined to a feed mechanism 31. This feed mechanism is shown in detail in the patent application of I. Walton Bader for Nailing Machine referred to in this specification. The mechanism has no bearing on this invention.

Within auxiliary valve chamber 26 a plurality of ports 32 are provided which are open to atmosphere. However an actuator 33 of the auxiliary valve is sealably and reciprocatingly movable within chamber 26. Actuator 33 bears an O-ring 34 thereupon which is disposed within a groove 35 within actuator 33.

A second O-ring 36 is disposed within a groove 37 upon actuator 33.

Conduit 24 abuts trigger valve 40. Trigger valve 40 is formed with a stem 41 which is formed with a scalable portion 42 which bears an O-ring 43 disposed within a groove 44. The opposite portion 45 of stem 41 is adapted to impinge against a handle 46 which is pivoted upon pin 47. Stem 41 also bears a fluted intermediate portion 48 so that air may pass through these flutes in order to operate the mechanism of this invention as will be subsequently explained.

Stem 41 is disposed within a chamber 49 and is normally maintained in sealed position by spring 50. Chamber 49 is sealed by means of a plurality of O-rings 51.

Conduit 24 abuts chamber 49. Chamber 49 also abuts conduit 52 which in turn is connected with chamber 53. Within chamber 53 is actuator 54 of valve structure 55. Actuator 54 bears an upper face 56 which is of larger cross-sectional area than its intermediate face 57 or its lower face 58. In the normal rest position of actuator 54 pressure air cannot reach the top of piston 14 since O-ring 59 seals the junction. Also actuator 54 is sealed in position within chamber 21 by O-ring 6 0. Also, in order to insure against any accidental displacement of the valve involved, a spring 61 is provided to hold actuator 54 in downward position.

A conduit 62 is provided in operative connection with actuator 54 which in turn joins a conduit 63. Conduit 63 is normally open to atmosphere. A bumper 64 is also provided to moderate the shock produced by movement of actuator 54. Actuator 33 of the auxiliary valve is formed with an upper face 65 and a lower face 66. Upper face 65 is of greater cross-sectional area than lower face 66.

With the foregoing specific description of this invention the operation thereof can now be explained.

In the normal rest position of a fastener driving machine to which the air return mechanism of this invention is connected, pressure air will pass from reservoir 22 into chamber 21 through 23. At the same time pressure air will pass from conduit 24 through junction portion 30 and into conduit 27. Also pressure air will pass from conduit 24 through conduit 67 into chamber 13. Pressure air will also pass through conduit 52 into chamber 53. In this normal rest position of the device actuator 54 of valve is in the down position since the air will impinge upon face 56 of actuator 54 which has a considerably greater cross-sectional area than intermediate face 57. At the same time pressure air will impinge upon face of actuator 33 as well as upon face 66 thereof. However face 65 has a greater cross-sectional area than face 66 and thus actuator 33 will be in the position shown in FIG. 2 and will block ports 32. When handle 46 is depressed so as to move stem 41 into an upward position conduits 24 and 52 will now become open to atmosphere since air can now exhaust through fluted portion 48 of stem 41 of the trigger valve. This will cause two things to happen. In the first place exhaust of air through conduit 24 will, of course, cause exhaust of air through conduit 27. At this point there will no longer be pressure air impinging upon face 65 of actuator 33. The pressure air acting on face 66 will therefore move actuator 33 into the rearward direction as shown in FIGS. 6 and 9. At this point ports 32 will be open and pressure air will exhaust from conduit 30 into conduit 24 and thence into atmosphere. This will, of course, effectively exhaust pressure air from chamber 13.

At the same time exhaust of air from conduit 52 will cause a release of pressure air from chamber 53. The pressure air in chamber 21 will now lift actuator 54 into the position shown in FIG. 5. This will permit pressure air to impinge upon the upper face 78 of piston 14. Since there is no longer any pressure air in chamber 13 below piston 14, piston 14 will move to the downward position and will drive rod 18 downwardly thus driving a fastener which would be placed within a magazine adjacent to rod 18 into work.

When handle 46 is released stem 41 of trigger valve 40 will move to its normal rest position. At this point conduits 25 and 52, and the conduits joined thereto, will no longer be open to atmosphere. Thus pressure air will now be present within element 28. This will, of course, move actuator 33 into the normal rest position shown in FIG. 2 and will thus close ports 32. This will, of course,

permit pressure air to be present within chamber 13. Since piston 14 is sealed and since the pressure air entering chamber 13 comes through conduit 67 which is located in the lower portion of this chamber beneath the lower face 69 of piston 14 this pressure air would normally apply an upper thrust to piston 14.

At the same time that this is occurring pressure air is no longer exhausted through conduit 52. As a result pressure air now will enter chamber 53 and since the area of face 56 is greater than that of face 57 actuator 54 will be moved to its normal rest position. Thus pressure air will not be entering the area 70 between upper face 68 of piston 14 and lower face 58 of actuator 54. However, at this point, conduit 62 is connected to conduit 63 and the pressure air is exhausted to atmosphere. This returns the piston to its normal position.

If handle 46 is again pulled the process will be repeated.

The above sets forth the manner in which the objects of this invention are achieved.

I claim:

1. A fastener driving machine comprising a housing, a first chamber within said housing, a piston sealably movable within said first chamber, a first valve adapted to permit pressure air to impinge upon one side of said piston so as to move said piston in one direction, a second chamber, a port within said second chamber open to atmosphere, at second valve adapted to permit pressure fluid to impinge upon the opposite side of said piston to move said piston in the opposite direction, said second valve having an actuator having tWo opposite faces with one face of larger area than the other, said smaller face normally blocking said port, a trigger valve, a conduit adjacent said larger face of said actuator operatively connected to said trigger valve, opening of said trigger valve opening said conduit to atmosphere and thus causing said actuator to move away from said port; said first and second valves being simultaneously operated.

2. A fastener driving machine as described in claim 1 including an additional conduit operatively connected with said first valve, opening of said trigger valve opening said additional conduit to atmosphere.

FOREIGN PATENTS 1/ 1963 Great Britain.

PAUL E. MASLOUSKY, Primary Examiner US. Cl. X.R. 

